pickup notes and measures

An example in 4/5 time of an opening
measure with pickup notes.

Once a meter has been set, the notes in each
measure, or bar, must add up exactly to the
number of beats it specifies. The exception
to this rule is the first bar, which may contain fewer beats than the time
signature specifies. When this happens, the first measure is called
a pickup measure. The notes themselves are called pickup
notes.